Installed with SPARK Pro¶
The provers Alt-Ergo, CVC4 and Z3 are installed with the SPARK tool. By
default, GNATprove uses prover CVC4 only. Switch
--level changes the
default to use one or more provers depending on the chosen level (see
Running GNATprove from the Command Line). Switch
--prover allows to
use another prover, or a list of provers. Prover names
z3 are used to refer to the versions of provers Alt-Ergo, CVC4 and Z3
that are installed with the SPARK toolset. The string
alt-ergo can also
be used to refer to Alt-Ergo. Using the switch
--prover=all, one can select
all three built-in provers, in the order
cvc4, z3, altergo. More information
on Alt-Ergo, CVC4 and Z3 can be found on their respective websites:
Installed with SPARK Discovery¶
In this case, only prover Alt-Ergo is installed with the SPARK tool. Hence,
by default GNATprove only uses prover Alt-Ergo. In particular, switch
--level has no impact on the use of different provers, and
will only select Alt-Ergo.
Installed with SPARK Community¶
The provers Alt-Ergo, CVC4 and Z3 are installed with the SPARK tool.
Other Automatic or Manual Provers¶
Updating the Why3 Configuration File¶
GNATprove can call other provers, as long as they are supported by the Why3 platform (see complete list on Why3 webpage). To use another prover, it must be listed in your Why3 configuration file.
To create or update automatically a Why3 configuration file, call the command
<spark2014-install>/libexec/spark/bin/why3config --detect-provers. It
PATH for any supported provers and adds them to the default
.why3.conf in your
HOME, or a configuration file
given in argument with switch
-C <file>. This file consists of a few
general settings and a section for each prover which is supported.
Note that GNATprove never reads the default configuration file
HOME. You need to pass the configuration file explicitly with
--why3-conf=<file>. Any prover name configured in this configuration
file can be used as an argument to switch
Note that using this mechanism, you cannot replace the definitions provided
with the SPARK tools for the provers
If more than one prover is specified, the provers are tried in order on each VC, until one of them succeeds or all fail. Interactive provers cannot be combined with other provers, so must appear on their own.
gnatprove has support for the Coq interactive prover, even though Coq is
not part of the SPARK distribution. If you want to use Coq with SPARK, you
need to install it yourself on your system and put it in your
environment variable. Then, you can simply provide
gnatprove. Note that the only supported version currently is Coq 8.5.